The command "env | grep OMPI" output nothing but a blank line
from my script. Anything I should set for mpirun?

On the other hand, you may get reminded that I found you
discussed some similar issue with Jonathan Dursi. The difference
is that when I tried with --mca btl_sm_num_fifos #(np-1), it does
not work with me, and I did find those files in the tmp directory that
sm mmaped in(shared_mem_pool.ibnode001, etc), but for some
mysterious reason, it hang at MPI_Init, so these files are created
when we call MPI_Init?